Abstract:
In this study, the influence of cyclic strain amplitude on the evolution of cyclic stress–strain
response and the associated cyclic deformation mechanisms in 316LN stainless steel with
varying nitrogen content (0.07 to 0.22 wt pct) is reported in the temperature range 773 K to
873 K (500 C to 600 C). Two mechanisms, namely dynamic strain aging and secondary cyclic
hardening, are found to strongly influence the cyclic stress response. Deformation substructures
associated with both the mechanisms showed planar mode of deformation. These mechanisms
are observed to be operative over certain combinations of temperature and strain amplitude.
For strain amplitudes>0.6 pct, wavy or mixed mode of deformation is noticed to suppress both
the mechanisms. Cyclic stress–strain curves revealed both single and dual-slope behavior
depending on the test temperature. Increase in nitrogen content is found to increase the tendency
toward planar mode of deformation, while increase in strain amplitude leads to transition
from planar slip bands to dislocation cell/wall structure formation, irrespective of the nitrogen
content in 316LN stainless steel.
